arm/x86/common: Add HAS_[ALTERNATIVE|EX_TABLE]

x86 implements all of them by default - and we just
add two extra HAS_ variables to be declared in autoconf.h.

ARM 64 only has alternative while ARM 32 has none of them.

And while at it change the livepatch common code that
would benefit from this.

Reviewed-by: Julien Grall <julien.grall@arm.com>
Reviewed-by: Ross Lagerwall <ross.lagerwall@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com> [relevant parts]
Suggested-by: Julien Grall <julien.grall@arm.com>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

xen/arch/arm/Kconfig

@@ -45,9 +45,6 @@ config ACPI
 config HAS_GICV3
 	bool
 
-config HAS_ALTERNATIVE
-	bool
-
 endmenu
 
 menu "ARM errata workaround via the alternative framework"

xen/arch/x86/Kconfig

@@ -7,8 +7,10 @@ config X86
 	select ACPI_LEGACY_TABLES_LOOKUP
 	select COMPAT
 	select CORE_PARKING
+	select HAS_ALTERNATIVE
 	select HAS_CPUFREQ
 	select HAS_EHCI
+	select HAS_EX_TABLE
 	select HAS_GDBSX
 	select HAS_IOPORTS
 	select HAS_KEXEC

xen/common/Kconfig

@@ -11,9 +11,15 @@ config COMPAT
 config CORE_PARKING
 	bool
 
+config HAS_ALTERNATIVE
+	bool
+
 config HAS_DEVICE_TREE
 	bool
 
+config HAS_EX_TABLE
+	bool
+
 config HAS_MEM_ACCESS
 	bool
 

xen/common/livepatch.c

@@ -641,7 +641,7 @@ static int prepare_payload(struct payload *payload,
                                   sizeof(*region->frame[i].bugs);
     }
 
-#ifndef CONFIG_ARM
+#ifdef CONFIG_HAS_ALTERNATIVE
     sec = livepatch_elf_sec_by_name(elf, ".altinstructions");
     if ( sec )
     {
@@ -672,7 +672,9 @@ static int prepare_payload(struct payload *payload,
         }
         apply_alternatives(start, end);
     }
+#endif
 
+#ifdef CONFIG_HAS_EX_TABLE
     sec = livepatch_elf_sec_by_name(elf, ".ex_table");
     if ( sec )
     {